Not applicable.
Not applicable.
1. Field of Invention
This invention relates to a device and method for a dental articulator for use with dental model casts. Specifically, the invention describes a dental articulator that is easily adjustable by the dental laboratory technician and/or dentist to align as desired the upper and lower dental model casts.
2. Related Art
Dental articulators, which hold and align together positive dental impressions, are well known in the prior art. Articulators are used to align the upper (maxilla) dental model with the lower (mandible) dental model, to simulate current or desired occlusion. By recreating the teeth and their occlusion (alignment) in model form, false teeth, caps and other dental prosthetics can be made in the precise size and shape necessary for the patient""s mouth.
To create the dental models (casts), the dentist makes a negative impression of the patient""s teeth. This impression may be a full mold (bilateral) or a partial quadrant mold (unilateral). The impression is obtained by filling a tray with thermoplastic material, and holding it against the patient""s teeth and gums. After the thermoplastic material partially hardens (sets up), the tray is removed, leaving the negative impression of the teeth.
To form a positive impression of the teeth and their position, pourable hardenable stone, often called yellow stone, is poured into the negative impression. The positive impression is allowed to harden, and is then removed from the negative impression, forming a precise positive model of the teeth and their placement. The hard positive impression is then pressed into a forming mold containing new yellow stone. This yellow stone is in a flowable state and forms the base of the dental cast. The positive impression bonds with the new yellow stone base, excess yellow stone is scraped away, remaining yellow stone is allowed to harden, and the complete cast is now formed. This cast is then removed from the forming mold.
The casts (upper and lower) are then attached to a dental articulator, which emulates the patient""s jaw for aligning the upper and lower teeth/casts.
The prior art describes various devices and methods for fashioning and securing the dental cast base to the positive impression. Prior art also describes various devices and methods for securing the dental casts to a dental articulator.
Representative of the early prior art for dental cast bases are devices described in the Tuccillo et al. U.S. Pat. No. 3,510,947 (May 12, 1970) and the Beckwith U.S. Pat. No. 4,319,875 (March 16, 1982). These patents utilize bases having female plastic snap receivers. The positive impressions are fabricated with male studs, which snap into the female snap receivers of the base. This requires precise alignment of each male stud to properly mate with the female receiver. Repeated use wears down the male stud, causing loose snapping with the female receiver, thus making the alignment loose.
An alternative base system is described in the Cho U.S. Pat. No. 5,622,497 (Apr. 22, 1997). A plastic base is adhered to a positive impression with a layer of stone material. The plastic base has a slot in which a disk is inserted and secured with a setscrew. The disk is attached to a stem having a ball at the other end, which connects to a reusable articulator. The system is requires plastic bases that are relatively expensive, as is the non-disposable dental articulator.
The most common type of base system, however, is the type utilized in the Huffman series of U.S. Pat. Nos. (4,533,323; 4,548,581; 4,734,033; 4,842,242). These patents and several others utilize base formers. Soft stone material is placed into a (typically) rubber base former, having a continuous sidewall, a floor and an open top. A hard positive impression is pressed into the soft stone material, excess overflow material is scraped away, and the soft stone material allowed to harden, adhering to the positive impression. The base and positive impression combine to form the dental cast, which has a uniform appearance due to the similar stone used in both the base and positive impression.
Dental casts formed by pressing positive impressions into base formers are affixed to dental articulators in a variety of methods in the prior art. Young (U.S. Pat. No. 5,605,456xe2x80x94Feb. 25, 1997) utilizes a cam clamp of the type used to secure automotive hoses. This hose clamp is wrapped around the base of the dental cast, and secured to a substantial dental articulator. Callne (U.S. Pat. No. 5,221,203xe2x80x94Jun. 22, 1993) utilizes a wire loop that clips into brackets integral with the top of the base. The wire loop is attached to a screw wheel adjustable dental articulator. Both systems require articulators that are difficult to use and are expensive.
The Huffman patents utilize a variety of means to secure the dental base/cast to an articulator. Huffman utilizes a disposable single-use plastic articulator having hinged articulator arms with socket balls that snap into retention sockets mounted to the dental cast base. The retention sockets may be inserted into the still soft stone (Huffman ""323), which requires the xe2x80x9cproficiency and expertise of the technicianxe2x80x9d to decide when to insert the mounting such that a proper alignment and securement is achieved. Other Huffman methods involve slots formed in the base by a shelf protruding into the interior cavity of the base former. When the former is removed (peeled off), slots and/or channels remain, into which a ridge tab is inserted and glued. The ridge tab has a socket that accepts a socket ball of the single-use articulator. When the upper and lower casts are aligned, a drop of quick drying glue is placed on the socket ball, and held until set. Some of the limitations of the Huffman devices are 1) the difficulty in positioning the upper and lower casts while gluing their socket joints; 2) inability to make adjustments after gluing the socket joints; 3) inability to make adjustments/corrections to the lateral and vertical placement of the ridge tabs after gluing; 4) difficulty in storing dental casts due to space taken by the non-removable articulator; and 5) expense associated with not being able to reuse articulators on different casts.
It would therefore be useful improvement of the prior art for a dental articulator system to utilize existing techniques for forming positive impressions, mounting these positive impressions on bases that use common stone material, and is flexible in adjustability during and after attachment to a re-usable articulator.
Accordingly, the objectives of this invention are to provide, inter alia, a new and improved dental articulator that:
is easily adjustable;
is inexpensive;
does not require the use of glue; and
can interchange and re-use articulator arms between different sets of casts.
These objectives are addressed by the structure and use of the inventive device and method. Re-usable articulator arms attach via ball and socket joints to a base clip, which is adhered to the dental cast base during the base formation process. Gross horizontal alignment is accomplished by a plurality of female recesses that accommodate male bulbs of a clip that attaches to the articulator arm via a screw adjustable ball and socket joint. Vertical adjustment and fine horizontal adjustment are accomplished by adjusting the orientation of the articulator arm ball and socket joint.
Other objects of the invention will become apparent from time to time throughout the specification hereinafter disclosed.